Revert "cros_generate_update_payload: Switch update_engine to major version 2"

This reverts commit 9201a4e1a9369d1618bc8737a97d9f6ded6d6e3e.

Reason for revert: <crbug.com/899786 - The paygen itself is working fine, but the update_payload_check failed>

Original change's description:
> cros_generate_update_payload: Switch update_engine to major version 2
>
> Per this change, we switch the update payload generation on the server side to
> major version 2. This new version includes smaller payloads (5%-10%) and has the
> capability to install multiple partitions (in comparison to a fixed two, kernel
> and root.) This affects all boards. For more information about the client
> support and the needed stepping stone refer to the attached issue.
>
> BUG=chromium:794404
> TEST=cros flash
> TEST=paygen release builders tryjob
>
> Change-Id: I9e4cc9391fd0c5d5720e980f450882d9385c7061
> Reviewed-on: https://chromium-review.googlesource.com/1234822
> Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
> Tested-by: Amin Hassani <ahassani@chromium.org>
> Reviewed-by: Don Garrett <dgarrett@chromium.org>
> Reviewed-by: Sen Jiang <senj@chromium.org>

Bug: chromium:899786
Change-Id: I41c61c50f0fac921922007656f750bc2ee205f82
Reviewed-on: https://chromium-review.googlesource.com/c/1305356
Commit-Queue: Amin Hassani <ahassani@chromium.org>
Tested-by: Amin Hassani <ahassani@chromium.org>
Trybot-Ready: Amin Hassani <ahassani@chromium.org>
Reviewed-by: Don Garrett <dgarrett@chromium.org>
Reviewed-by: Amin Hassani <ahassani@chromium.org>
diff --git a/scripts/cros_generate_update_payload_unittest.py b/scripts/cros_generate_update_payload_unittest.py
index dd60302..ddcb6c9 100644
--- a/scripts/cros_generate_update_payload_unittest.py
+++ b/scripts/cros_generate_update_payload_unittest.py
@@ -8,7 +8,6 @@
 from __future__ import print_function
 
 import os
-import tempfile
 
 from chromite.lib import cros_build_lib
 from chromite.lib import cros_test_lib
@@ -111,8 +110,6 @@
     }
     self.PatchObject(cros_build_lib, 'GetImageDiskPartitionInfo',
                      return_value=fake_partitions)
-    self.PatchObject(tempfile, 'NamedTemporaryFile',
-                     return_value=type('file', (object,), {'name': temp}))
     cros_generate_update_payload.main([
         '--image', '/dev/null',
         '--src_image', '/dev/null',
@@ -120,10 +117,10 @@
     ])
 
     self.assertCommandContains([
-        '--major_version=2',
-        '--partition_names=root:kernel',
-        '--new_partitions=' + ':'.join([temp, temp]),
-        '--new_postinstall_config_file=' + temp,
-        '--old_partitions=' + ':'.join([temp, temp]),
+        '--major_version=1',
+        '--new_image=' + temp,
+        '--new_kernel=' + temp,
+        '--old_image=' + temp,
+        '--old_kernel=' + temp,
         '--rootfs_partition_size=4',
     ])